How do you check if the value exists before you update

Thikho

Hi All

I have a simple form that allows users to update the invoice received date to the current date which works fine , The user enter a waybillnumber and it will update.

I want to check if waybills exists before it send an update to the database, If they try to update a waybill that does not exist it should send an error message ,i need help with that

my form below

<?php
require ('paths.php');
define('VDAEMON', false);
require(REPOSITORY.'vdaemon/vdaemon.php');

//strip out anything malicious
submissionClean($_POST);

foreach($HTTP_POST_VARS as $varname => $value)
$formVars[$varname]=$value;

require_once("db_connect.php");

$query="SELECT * FROM Internal_Docs_waybills_outstanding WHERE WaybillNumber = \"".$formVars["WaybillNumber"]."\"";
$result=mysql_query($query) or die("Cannot Select from Internal Docs waybills outstanding ");
$row=mysql_fetch_array($result);

$formVars = array();
$formVars["Waybill_Date"]=$row["Waybill_Date"];
$formVars["Date_Invoice_Received"]=$row["Date_Invoice_Received"];
$formVars["Admin_Checked"]=$row["Admin_Checked"];
$formVars["WaybillNumber"]=$row["WaybillNumber"];

?>
<html>
<head>
<title><?php $pageTitle = 'Nikita DocProc System'; echo $pageTitle; ?></title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<meta name="keywords" content="<?php echo $keywords;?>" />
<meta name="description" content="<?php echo $description;?>" />
<link href="styles/main.css" rel="stylesheet" type="text/css" />
</head>
<body>

<div align="center">
	<div align="center" class="inner">
		<h2>Nikita DocProc</h2>
	<p>Please  press the "Submit" button to update the Date Invoice Recieved</p>

<form method="post" action="postupdate.php">
<table>

<tr>
<td><font class="normaltext">Waybill_Date</font></td>
<td><input type="text" name="Waybill_Date" 
value="<? echo $formVars["Waybill_Date"]; ?>" size=15></td>
</tr>

<tr>
<td><font class="normaltext">Waybill Number </font></td>
<td><input type="text" name="WaybillNumber" 
value="<? echo $formVars["WaybillNumber"]; ?>" size=15></td>
</tr>
<tr>
<td><input type="submit" value="Submit"></td>
</tr>

</div>
</div>
</body>
</html>

file to update

<html>
<head>
<title><?php $pageTitle = 'Nikita DocProc System'; echo $pageTitle; ?></title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<meta name="keywords" content="<?php echo $keywords;?>" />
<meta name="description" content="<?php echo $description;?>" />
<link href="styles/main.css" rel="stylesheet" type="text/css" />
</head>
<div>
<div align="center">
	<div align="center" class="inner">
		<h2>Nikita DocProc</h2>
		<?php

	foreach($HTTP_POST_VARS as $varname => $value)
	$formVars[$varname]=$value;

	require_once("db_connect.php");

	echo "<p>Date Invoiced Received updated<br><a href=\"index.php\">click here</a> to update another record<br></p>";
	$query="UPDATE Internal_Docs_waybills_outstanding set 
	Date_Invoice_Received= NOW() WHERE WaybillNumber  = \"".$formVars["WaybillNumber"]."\"";

	mysql_query($query) or die("Cannot Update Date Invoice Received on Internal Docs waybills outstanding ");;

	?>
	<p>Administrators <a href="http://www.tshisevhe.co.za/" target="_blank">CLICK HERE</a> to edit/add Documement Control Information.</p>
</div>
</div>
</body>
</html>

Krik

this query in your form page

$query="SELECT * FROM Internal_Docs_waybills_outstanding WHERE WaybillNumber = \"".$formVars["WaybillNumber"]."\"";

looks to see if the number is found so if the number isn't found don't let them see the form. Or disable relevant parts of the form. That way they can't submit an update to a non-existent record.

planetsim

Basically it would be before the update a select on the database to find the waybillnumber. e.g.

if ( mysql_num_rows( mysql_query( "SELECT WaybillNumber FROM Internal_Docs_waybills_outstanding WHERE WaybillNumber = '" . mysql_real_escape_string( $_POST["WaybillNUmber"]) . "' " ) )
{
 // dont update billnumber exists
}

[edit]beaten to the punch[/edit]

Thikho

I am getting confused now with the part of hiding the form , I only want to show error messages to the users, what im trying to achieve is to check if it exist before they update , if they try to update a waybill that does not exists it should tell them that it doesn't exist.

djjjozsi

when you build a database, you can set one or two fields as Unique.

if you insert or update an existing value you will get a duplicate error.

after you update that field watch the error codes:

mysql_errno() has a value 0 if there was no error in your query.

print its value after update to know which is the duplicate entry error code.

hello, jjozsi.

Krik

Thikho;10907815 wrote:
I am getting confused now with the part of hiding the form , I only want to show error messages to the users, what im trying to achieve is to check if it exist before they update , if they try to update a waybill that does not exists it should tell them that it doesn't exist.

The suggestion was to avoid a bunch of code duplication. What I suggested was to use code you already had verses adding more.

Since your form page already checks to see if the waybill number exists I thought you could just beef it up a bit and prevent the user from submitting the form.

But if that is too confusing you can use that same query in the update code to check if the waybill number exist and then run the update if it does or put out an error if it doesn't exist.

Both are the exact same process just applied to a different part of your code. It really breaks down to what is best for the user. My original suggestion was to designed so the user would know about the error before submitting data verses after they tried submitting and got an error.

Thikho

Thank you Krik i understand now and i have some progress already.